1. Field of the Invention
The present invention relates to an improvement on a lens barrier device which is disposed in front of a photo-taking lens of a camera.
2. Description of Related Art
As a result of the advancement of automating devices, reduction in size and arrangement for further zooming made during recent years, cameras have come to have highly convenient functions. A lens barrier device which is disposed in front of a photo-taking lens of the camera is one of such conveniences. Generally, the lens barrier device is arranged to automatically close a barrier into a stowed state in association with the actions of a zoom mechanism and a lens-barrel drawing-in mechanism.
Further, the diameter of a lens barrel which holds a photo-taking lens decreases more and more according to the advancement of reduction in size of the camera. Some of known such barrier mechanisms have come to be composed of four blade members as it is hardly possible to cover the lens barrel with two blade members. In Japanese Laid-Open Utility Model Application No. Hei 3-69133, there is disclosed a typical barrier mechanism of the four-blade structure. In such a conventional barrier mechanism, two outer blade members are located in front (or in rear) of two inner blade members with respect to axes which are parallel with the optical axis of the lens barrel, and the two outer blade members and the two inner blade members are arranged to overlap each other in an open aperture state, so that the barrier mechanism can be stowed within a small area. Therefore, a large photo-taking aperture can be obtained.
However, the barrier mechanism having the blade members in the above-stated manner necessitates a complex mechanism for driving the four blade members. The barrier mechanism thus requires a relatively large space and a great number of parts within the camera. Further, since the four blade members are disposed in such a way as to overlap in the direction of the optical axis, the size of the barrier mechanism increases in thickness, i.e., in the direction of the optical axis. Therefore, the arrangement of the conventional barrier mechanism causes an increase in total length of the lens barrel.
In accordance with one aspect of the invention, there is provided a lens barrier device for a camera, comprising a main blade member and an auxiliary blade member which are located on one and the same plane approximately perpendicular to an optical axis of a photo-taking lens, and a driving part which drives the main blade member and the auxiliary blade member to open and close, the auxiliary blade member being driven to open and close following the main blade member.
The above and other aspects and features of the invention will become apparent from the following detailed description of a preferred embodiment thereof taken in connection with the accompanying drawings.